Still a staple in one of my paladin decks with a single challenger and 6 secrets, built around pulling 3 of them out of hand on average, along with some silver hand shenanigans, working out quite well so far along with some Maiden of the Lake synergies. Got them pretty ladies in my deck ;)

Im just thinking that you rather play 1 drop, 2 drop, 3 drop, than secret keeper, secretkeeper + secret, more secrets? Yes you gain potential monster keepers but wouldt you rather have those secrets be summoned through Mysterious Challenger than playing them by themselves?